The present invention relates to a latching mechanism for the thrust reverser door of a jet engine, more particularly such a latching mechanism that will retain the thrust reverser door in the forward thrust position despite catastrophic failure of the jet engine components.
Aircraft jet engine thrust reversers are well-known in the art and enable the propulsive gas flow from the turbojet engine to be re-directed in a direction having a reverse thrust component for slowing or braking the aircraft. Pivoting door type thrust reversers are also well known in which one or more thrust reverser doors are pivotally attached to an engine cowling so as to be movable between forward thrust positions, in which the propulsive gases are directed in a forward thrust direction, and reverse thrust positions, in which the pivoting doors re-direct at least a portion of the propulsive gas flow into a direction having a reverse thrust component. Typically, such pivoting door type thrust reversers cover a reverse thrust opening through the cowling when in the forward thrust position and open the reverse thrust opening when in the reverse thrust position. The engine cowling may have a front frame to which the thrust reverser door actuator is mounted, the opposite end of the actuator being attached to the thrust reverser door. Longitudinally extending beam portions of the cowling connect the front frame of the cowling to a rear cowling portion and extend between circumferentially spaced apart thrust reverser doors. The thrust reverser doors may be pivotally attached to the beams on opposite lateral sides of the reverse thrust opening.
Thrust reversers also must include devices for locking the thrust reverser doors in their forward thrust positions. Known locking means typically comprise a latch affixed to the front frame structure of the cowling and a cooperating portion of the latch situated at a front portion of the thrust reverser door. Typically such locking devices are located at the front portion of the thrust reverser door and a corresponding location on the front frame of the cowling, but may also be located at opposite lateral sides of the door and corresponding locations on the cowling. Generally, the pivoting thrust reverser doors have their pivot axes located towards the rear of the thrust reverser door and are, therefore, self-opening due to the pressurized gases within the gas flow duct bounded by the cowling and the thrust reverser doors acting on the inner surfaces of the thrust reverser doors. It is also known to provide such thrust reverser doors with pivot axes located toward the forward portion of the doors, thereby rendering them self-closing by the pressurized gases acting on their inner surfaces. Usually pivoting door type thrust reversers have the forward portions of the thrust reverser doors move outwardly from the cowling when moving into the reverse thrust positions, although "scoop" type doors are also known in which the forward portion of the thrust reverser door moves inwardly into the gas flow duct.
As can be imagined, inadvertent deployment of the thrust reverser door to the reverse thrust position during aircraft flight may be catastrophic. Therefore, it is known to utilize redundant locking devices to prevent such inadvertent deployment. Despite these precautions, redundant latching and locking systems may be rendered ineffective in two situations. If a turbine rotor ruptures, severe damage may be caused to the jet engine, the cowling and to the thrust reversers. The debris from the ruptured motor may cause twisting of the front frame which, in turn, may cause force to be applied to the locks which may then disengage and no longer hold the thrust reverser door in its forward thrust position. In such instance, although the locks may be functional, the damage to the front frame, to which the locks are attached, may cause the lock portions to disengage. This problem is worsened when larger locking devices are utilized, since the probability of the locking device itself being impacted by the rotor debris is increased. Secondly, a fire in the turbojet engine may also cause the release of the locking devices due to the fire's effect on the control system for opening and closing the locking systems. Consequently, a fail-safe locking mechanism must address this possibility and preclude the opening of the thrust reverser door under these circumstances.
Even under normal operating circumstances, the stresses imposed upon the locking device are severe. Consequently, a reduction of these stresses will be advantageous and could prevent premature failure of the locking devices.